The invention relates to a magnetic tape cassette which comprises first and second winding reels, which each comprise a winding hub with an essentially cylindrical outer wall in which a recess is formed, as well as a flange on each side of the winding hub. The first end of the magnetic tape contained in the cassette is attached to the first winding hub and the second end of said magnetic tape to the second winding hub, so as to enable the tape to be wound from the first winding reel to a second roll on the second winding reel and back from the second winding reel to a first roll on the first winding reel. First and second clamping members fix the first and the second end of the magnetic tape to the first and the second reel hubs respectively, by pressing the clamping members into the recesses in the winding hubs.
Magnetic tape cassettes having winding reels with flanges are employed for recording and reproducing video signals by means of so-called video recorders. In a known magnetic tape cassette for a video recorder, a so-called video cassette, the clamping member has a U-shaped cross-section with a wide crosspiece and short limbs, which limbs are formed with integral outwardly projecting feet which engage behind wall portions of the winding hub at the location of undercuts of the recess in the winding hub.
It is obvious that the mass manufacture of magnetic tape cassettes demands the use of machines for automatically attaching the magnetic tape to the winding hubs. However, it is desirable that magnetic tape can also simply be attached and detached by hand, so as to enable a fault during the manufacture to be corrected and a cassette to be repaired in the event of breakage of the tape.
From The German Auslegeschrift No. 2 100 959 published May 18, 1978 a device is known for fixing of a magnetic tape to a winding hub with the aid of a clamping member of the type mentioned above. This device serves for fitting clamping members in winding hubs without flanges. The winding hubs are arranged on a slide which is moved in the direction of an assembly station, the clamping members being conveyed to the station by the action of gravity and being temporarily retained by locally provided means. When the winding hub arrives at the mounting station one of the limbs of the U-shaped clamping member is pressed into a recess of the winding hub at a specific instant, after which the clamping member is tilted and is fitted into the recess by means of a pivotable mounting finger, which exerts pressure on the foot of the other limb. However, such a device cannot be used if flanges are situated on both sides of the winding hub, because these flanges prevent the winding hub from being conveyed to the assembly station. Mounting a clamping member in a winding hub with flanges on both sides is therefore far more difficult than mounting a clamping member in a winding hub without flanges. The aforementioned known magnetic tape cassette therefore has an opening in at least one of the flanges of the winding hub, namely at a location corresponding to the recess in the winding hub. Through the opening in the flange a clamping member can be inserted in a direction parallel to the axis of rotation of the winding reel until it faces the recess in the winding hub, after which the clamping member can be pressed into the winding hub in the radial direction with the aid of a tool, which is radially inserted between the flanges or which is passed through the opening in the flange and subsequently moved in the radial direction. The opening in the flange also serves for removing the clamping member. Through the opening a tool can be fitted behind the cross-piece of the U-member, after which the clamping member can be ejected in the radial direction.
The known magnetic tape cassette has some drawbacks. For example, for pressing the clamping member into the recess of the winding hub an intricate maneuver is required, as a result of which the movements of the clamping member, in particular during the press-in operation when the clamping member cannot be retained, are not fully controlled. For retaining and fitting the clamping member the automatic assembly tool should be provided with parts which are movable relative to each other. In the case of a magnetic video tape, which in certain cases has a thickness of only 15 .mu.m or even less, a slight misalignment of the magnetic tape relative to the winding hub may already give rise to winding problems. Creases may be formed in the magnetic tape, which propagate outwards in the radial direction through many layers of the tape, so that at least a part of the roll is wound irregularly, which may lead to faults in the recording and reproduction of the signals. Also, at least one of the flanges should be formed with an opening. During manufacturing the opening in the flange should be aligned relative to the recess in the winding hub. The opening in the flange affects the appearance of the winding reel. A further drawback is that during removal of the clamping member, when a manual tool such as a screwdriver is used, and the clamping member can be removed in the radial direction, the clamping member may readily drop and may thus be lost.